Hardcoating Technologies Ltd (HTL) in Munroe Falls, OH,was founded in 1996 because of quality issues. Theircommitment to quality has taken them from coating67,000 cutting tools in 1996 to 1.7 million plus in 2006

and on pace for more than two million in 2007.HTL is the sister company of cutting tool manufacturer SGS, the

first domestic cutting tool manufacturer to attain ISO 9001 status inthe U.S. SGS is also headquartered in Munroe Falls, where it manu-factures a variety of cutting tools, drills, end mills, burs, reamers,routers, countersinks and specials that are sold worldwide in 66countries. The tools manufactured by SGS are used in manufacturingprocesses by industries such as aerospace, automotive, medical,power generation, foundry/casting and mold and die. A key sellingpoint and quality standard for these tools is the significantlyincreased tool life and production capacity that occurs when the toolsare coated via physical vapor deposition (PVD) with a coating appro-priate to their substrate and the operation they will perform.

In 1996, the coating operation was sourced to outside vendors bySGS and the results were less than perfect, with coated tools toooften coming back damaged. SGS’s solution to the coating problemwas to create their own coating company, HTL, to get the job doneright. Today, HTL offers four types of PVD coatings to SGS andmore than 200 other customers in the U.S. ranging from tool manu-facturers to tool distributors, and from end users (such as automotive,aerospace, medical and mold and die) to tool re-workers and re-grinders. These coatings are HTL’s original, general purpose coating,Titanium Nitride (TiN), plus three additional coatings: TitaniumCarbonitride (TiCN, Aluminum Titanium Nitride (AlTiN), HTL’sproprietary formula and their most popular coating, and TitaniumDiBoride (TiB2), which HTL calls “the toughest coating ever, rec-ommended for use with silicon aluminum alloys, titanium alloys,magnesium alloys and copper alloys.”

Precision Cleaning Challenges

HTL vice president Bob Stauffer reports that the company coatstools 24 hours a day, five days a week. Precision cleaning—“pristinecleaning” according to Stauffer—is essential to the success of theprocess, as none of the coatings will adhere correctly on less thanscrupulously clean substrates.

When HTL was first formed in 1996, they purchased an automat-ed cleaning line featuring one 40 kHz ultrasonic cleaning station withcaustic chemistry, one ambient plastic cleaning tank with acid chem-istry, one 40 kHz ultrasonic rinse, two additional rinses (the final

Case Study

Re-Thinking Precision Cleaning of Tools Prior to Coating for Increased Throughputand Superior AdhesionCheryl Larkin

In the cutting tool world, an appropriately coated tool can allow

increased feed of product and speed of cutting up to 50 percent,

and can increase tool life up to 10 times. At HTL, the new

Miraclean cleaning line has eliminated manual scrubbing labor

and increased throughput.

The end result of successful precision cleaning at HTL is successful PVD coating on a

wide variety of tools and substrates.

Image courtesy of HTL.

rinse being DI water), a blow off station and a re-circulating hot airdry. The system automation was a PLC controlled hoist, but through-put was limited by the fact that the hoist stayed with a specific loadat all times. “As growth required it, we got around the hoist designand increased our production by manually stopping the line in theblow off station and re-starting it with a new load at the cleaning end.Then we’d manually blow off the first load and move it to the dryerwhile the hoist automatically started the next load through the clean-ing and rinsing, so that we could at least be working on two loads atonce,” says Stauffer.

Another challenge presented by the original cleaning line was thatnot all parts came out of it clean. Many of the re-worked and re-ground tools that arrived to be coated are heavily soiled, and some,such as rotary files, would come off the cleaning line with carbideswarf still stuck in the gullets of the flutes. This meant additional

hand cleaning, which Stauffer estimates took one and a half to twohours per coating load.

With throughput demands growing, HTL looked to MiracleanUltrasonics in Ashville, NY, to help develop a new, higher produc-tion and more flexible machine. In addition to designing and build-ing ultrasonic parts cleaning, passivating, electropolishing andanodizing lines, Miraclean is also a division of ChautauquaChemicals Co., Inc., and specializes in identifying and/or developingcleaning chemistries for specific applications.

Cleaning, Rinsing and Drying Solutions

Miraclean Technical Director Brian Sutton spearheaded theMiraclean side of the partnership to develop a more productivemachine that would also eliminate the need for hand cleaning of toolsalready processed in the automated cleaning line. A review of thetools to be cleaned in the line revealed that there were three cate-gories of soils: (1) lightly soiled new tools, (2) heavily soiled re-worked or re-ground tools and (3) high speed steel tools. Soilsincluded oil-based grinding solutions, machining oils, polishingcompounds, oxidation and grinding burns.

The cleaning detergent used in the original cleaning line was ahigh caustic, chelated solution that sometimes failed to remove thesoils from the tools and contributed to carbide leaching. Instead,Miraclean recommended and proved a mildly alkaline, non-chelatedchemistry that minimizes leaching and also splits oil. In conjunctionwith the cleaning tank design, this split oil is then skimmed from thesurface via a sparger and trapped in a separate overflow weir. Oncein the weir, the oil can’t redeposit on clean parts on exit and is isolat-ed for disposal.

To further improve the process, Miraclean outfitted the first alka-line cleaning tank with 25 kHz immersible ultrasonic transducers.This frequency is characterized by larger bubbles which implodemore violently than the smaller 40 kHz bubbles, thereby supplying acleaning action in the first alkaline tank that is more aggressive thanthe 40 kHz on the original line. Vertical agitation was also added tothe first alkaline clean to provide additional mechanical action tobreak the soil bond on heavily soiled or steel tools.

Testing also indicated that adding a second alkaline cleaning sta-tion to the new line would give superior cleaning results. The secondalkaline clean station was then equipped with 40 kHz ultrasonics. Asa complement to the 25 kHz on the first cleaning station, the lessaggressive but smaller bubbles produced by the 40 kHz ultrasonicfrequency access tinier geometries to provide additional cleaningaction. Both cleaning tanks are also equipped with electric heat, dualfilter systems to remove particulate and spargers to skim floatingoils. In tandem, the two cleaning stations provide gross cleaning inthe first cleaning station and fine cleaning in the second.

The acid cleaning station on the new line changed from a static,ambient bath on the original line to a third heated ultrasonic cleaningstation equipped with 40 kHz ultrasonics, electric heat, a filter sys-tem to remove particulate and a sparger system to skim surface oilsinto the separate overflow weir for disposal. The acid cleaner testedand proved by Miraclean is a milder pH acid that is safer to use, moreenvironmentally friendly for disposal and gives superior results in

Carbide leaching that can occur during cleaning of cutting tools prior to PVD coating if

chemistry, time or process steps are too aggressive.

A successfully cleaned cutting tool with no leaching.

conjunction with heat and ultrasonics in removing oxidation and grind-ing burns. HTL’s Stauffer points out that on the original cleaning line thecontents of the high caustic cleaning bath and the low pH acid cleaningbath had to be combined when drained to meet local effluent standards.The lower pH alkaline chemistry and the milder acid cleaner on the newline now make this step unnecessary.

Next, Miraclean suggested three changes to the rinse tank configura-tion for the new line. First, the number of rinses on the line wasincreased. The original line featured a heated double counter-flow (cas-cade) rinse after the caustic clean and a single heated DI rinse after theacid clean. The new line is equipped with two additional rinses, includ-ing an ambient rinse after the first alkaline clean and after the acid cleanand a triple counter-flow rinse at the end of the line. The triple counter-flow is to take advantage of the principles of dilution with each addedrinse improving dilution (and therefore reducing residue) exponentially.At the same time, the counter-flow feature means that the same water isbeing used three times with conservation and cost-savings benefits. Thecounter-flow rinses are fed by HTL-supplied DI water for spot-freeresults.

The second change to the rinse configuration was from 40 kHz ofultrasonics in the first counter-flow rinse on the original line to 72 kHzof ultrasonics on the first counter-flow rinse of the new line. AsMiraclean’s Sutton explains, 72 kHz is a still-gentler ultrasonic frequen-cy that is especially appropriate for this application, providing the advan-tages of ultrasonic rinsing (driving solution into complex geometries)while minimizing the potential for damage from DI water, which can beaggressive on certain substrates.

The third change to the rinse tank configuration was the addition of aconductivity analyzer to the final rinse to call for fresh DI water when thequality in the last rinse dips below HTL specified standards. This assuresthat the last water in contact with the tools is acceptable quality withouthaving to flow the rinse continuously, and is further assurance of spot-free rinsing.

As on the original line, the final rinse is followed by an air blow offstation, but this was re-designed on the new line to eliminate problemsthat occurred on the original line. Stationary, side-mounted air kniveshave been replaced on the new line with an overhead moving air knifecontrolled by the PLC. HTL’s Stauffer—who was instrumental in thedesign—notes that the newly designed blow off effectively removeswater without blowing the parts out of their fixtures as sometimes hap-pened with the side-mounted air knives on the old system. Miraclean’sSutton adds that the blow off is an important step to further decrease thechance of water spotting on the clean parts, which could result in coatingrejects. The feed for the air blow off is food quality filtered air. The airblow off station is followed by a re-circulating hot air dryer equippedwith a HEPA filter to remove particulate. The dryer also has a connectionfor a nitrogen line to augment the drying, but the dryer has functionedefficiently without nitrogen to date, and HTL has never hooked it up.

Miraclean system’s standard automation package allows for three pro-grams or recipes to run simultaneously, a feature which HTL uses regular-ly for the wide range of tools and soil levels that it has to clean. To protectthe cutting edges of the tools from being cleaned, loads are processed asbatches of tools fixtured in customized racks designed by HTL, which thenfit into carriers supplied by Miraclean. This arrangement gives HTL g r e a tflexibility to respond to new types of tools, as new, part-specific racks caneasily be integrated with the carrier system. At this time, HTL uses 60 to

Multiple loads and recipes move simultaneously through the Miraclean ultrasonic

cleaning line which has tripled precision cleaning throughput at HTL.

70 modular racks, some plastic, some stainless steel and more than1,000 customized inserts in various substrates to hold the tools.

To operate the cleaning line, the operator simply places a loadon the load station, selects the program for the batch and pressesstart on the color touch screen. The hoist then tracks each load,moving loads according to their respective program parametersthrough each appropriate process step. As many loads as there areprocess stations can be processed at one time. Manual operation,if preferred, can be accomplished via a joystick. The PLC can alsobe remotely accessed by Miraclean engineers and programmersvia modem for programming changes or troubleshooting ifrequired, and recipe modifications can be made on site by HTL orremotely by Miraclean.

Feed and Speed

“Feed and speed” is what coated cutting tools provide to theirend users according to Stauffer. In the cutting tool world, anappropriately coated tool can allow increased feed of product andspeed of cutting up to 50 percent, and can increase tool life up to10 times.

“Feed and speed” is what the new Miraclean cleaning line has pro-vided to the coating team at HTL as well. Since the installation of theMiraclean line, manual scrubbing labor has been eliminated at a sav-ings of four hours per day X 280 days per year = 1,120 hours peryear. Throughput from the cleaning line has increased from 3,000 to4,000 parts in 24 hours with the old line to 8,000 to 12,000 parts in18 hours with the new line. Regular, rigorous tool inspections con-ducted by HTL show that tools are at least as clean as before, but nowwithout hand cleaning.

As a bonus, the tweaking of recipes on the new cleaning line( c h e m i s t r y, time and process steps) has resulted in reduced carbideleaching on affected tools, an important quality consideration, asleaching undermines surface quality, which in turn can lead to de-lam-ination (flaking, failure) of a coating that is subsequently applied.

HTL’s customers trust the results. One Western U.S. manufacturer,

for example, ships parts to HTL where they’re cleaned, coated, final-packaged and shipped directly to distributors—in the ultimate nod toHTL’s quality control. “Any time you can clean more parts and stillmaintain or exceed standards, you’re definitely moving in the rightdirection,” says Stauffer, who was instrumental in starting HTL backin 1996 and is totally committed to quality. He adds that there has notbeen one tool failure or reject attributed to cleaning since theMiraclean system was installed. PCM

Cheryl Larkin is East Coast territory manager for MiracleanUltrasonics (Ashville, NY). She holds an A.B. from Wheaton Collegein Norton, MA, and is based in New Jersey. Her work in precisioncleaning includes extensive experience in medical device cleaning,passivating and automated penetrant inspection. She can be reachedat (716) 763-4343.

©2007 Communication Technologies, Inc., All Rights Reserved.

Reprinted from Process Cleaning Magazine. Contents cannot be reprinted without permission from the publisher.